The word(s) "disbelief" appears 37 time(s) in 35 verse(s) in Quran in Muhammad Pickthal translation.

(11) Lo! those who believe, then disbelieve and then (again) believe, then disbelieve, and then increase in disbelief, Allah will never pardon them, nor will He guide them unto a way.

(12) Then because of their breaking of their covenant, and their disbelieving in the revelations of Allah, and their slaying of the prophets wrongfully, and their saying: Our hearts are hardened - Nay, but Allah set a seal upon them for their disbelief, so that they believe not save a few -

(13) And because of their disbelief and of their speaking against Mary a tremendous calumny;

(14) O Messenger! Let not them grieve thee who vie one with another in the race to disbelief, of such as say with their mouths: "We believe," but their hearts believe not, and of the Jews: listeners for the sake of falsehood, listeners on behalf of other folk who come not unto thee, changing words from their context and saying: If this be given unto you, receive it, but if this be not given unto you, then beware! He whom Allah doometh unto sin, thou (by thine efforts) wilt avail him naught against Allah. Those are they for whom the Will of Allah is that He cleanse not their hearts. Theirs in the world will be ignominy, and in the Hereafter an awful doom;

(15) The Jews say: Allah's hand is fettered. Their hands are fettered and they are accursed for saying so. Nay, but both His hands are spread out wide in bounty. He bestoweth as He will. That which hath been revealed unto thee from thy Lord is certain to increase the contumacy and disbelief of many of them, and We have cast among them enmity and hatred till the Day of Resurrection. As often as they light a fire for war, Allah extinguisheth it. Their effort is for corruption in the land, and Allah loveth not corrupters.

(16) Say O People of the Scripture! Ye have naught (of guidance) till ye observe the Torah and the Gospel and that which was revealed unto you from your Lord. That which is revealed unto thee (Muhammad) from thy Lord is certain to increase the contumacy and disbelief of many of them. But grieve not for the disbelieving folk.

(17) And if they break their pledges after their treaty (hath been made with you) and assail your religion, then fight the heads of disbelief - Lo! they have no binding oaths - in order that they may desist.

(18) It is not for the idolaters to tend Allah's sanctuaries, bearing witness against themselves of disbelief. As for such, their works are vain and in the Fire they will abide.

(19) O ye who believe! Choose not your fathers nor your brethren for friends if they take pleasure in disbelief rather than faith. Whoso of you taketh them for friends, such are wrong-doers.

(20) Postponement (of a sacred month) is only an excess of disbelief whereby those who disbelieve are misled; they allow it one year and forbid it (another) year, that they may make up the number of the months which Allah hath hallowed, so that they allow that which Allah hath forbidden. The evil of their deeds is made fairseeming unto them. Allah guideth not the disbelieving folk.